Discussion on another forum revolved around a light sporter barrel, and brake/suppressor mount install.

Barrel diameter was not sufficient for a substantial enough shoulder for the required 5/8" threads- and it was suggested that the muzzle could be used as the torque shoulder instead of the typical way it's done.

I'll admit I've never heard of doing it that way and was going to instinctively dismiss it, but I can't see a reason why it wouldn't work?

If the muzzle is faced off precisely at 90 degrees to the bore same as you would a barrel shoulder, and a substantial flat is left after cutting the crown (the crown could be faced back same as a typical barrel shoulder to time the brake) is there a fatal flaw in this method?

It would work just fine although the installation would be on the ugly side. I guess one could call it "tactical" and it would be alright. Anything goes in that category. Regards, Bill

Done, done and done to death.

When you bore the hole for the thread extension, do it with the closest slot mill to the ID of the thread. I generally bore the hole about .550, or .050 deeper than standard to give a full .500 of thread. Run your ID reamer in .020 inch short. Then rigid tap the thread in the lathe or mill. When cutting the extension on the barrel. Face the muzzle square leaving a small amount that can't be reached because of the rotating dead center. Then, with the barrel between centers, recut the crown using a piloted 60 degree cutter making sure that you clean up what you couldn't reach while squaring up the face. When you cut the extension make a .050 long cut on the nose of the muzzle a couple thousandths under the diameter of the end mill that you rough plunged the hole with. The rest is straight forward like any other brake except it will shoulder on the muzzle.

Like Bill says, you lose the blended look of the taper on the brake meeting the OD of the barrel.

Done it many times; what is the issue? Most of the brakes I install are so big as to not make a blend into the barrel OD; I, and others, like them big and cylindrical; like you see on cannons. The one rule of brakes is, the more gas you divert, the more efficient they are. Some of the small barrel size brakes I have used do little in that regard.

quote:

Originally posted by dpcd:
The one rule of brakes is, the more gas you divert, the more efficient they are. Some of the small barrel size brakes I have used do little in that regard.

Tom hit the nail on the head as to effectiveness. A friend of mine had a karate studio here in town and had a bunch of those baseball base's with load cells under them to measure punch force in grams. After a few to many drinks one night we came up with a hare brained idea and the next day I met him at the range with a couple of guns and every brake design that I could lay my hands on. We mounted the force gauge to a telephone post, tied in his computer and started measuring the recoil of every different brake on a 30-06 and a 300 Winchester. What we found was exactly what Tom said. The more gas that you divert sideways, the more the recoil was reduced. When you angled the holes back the brakes worked like the diverter on a Harrier Jet and the recoil was reduced further. When you angled the holes forward the recoil increased. Back at the lab, my shop, we ran the numbers and there was a very high correlation to the amount of recoil reduced to the square inches of hole in the brake. Large holes verses small holes made little difference. Gills or slots verses round holes made very little difference. Despite all of the claims, it comes down to how many square inches of hole you have to let the gas out. Probably the most effective of the brakes is the standard KDF brake and it's variants. The staggering of the holes allows you to have more hole, without making the device overly large or jeopardizing structural integrity. Super large brakes with gills, slots or large holes really reduce no more recoil as long as the square inches of holes is about the same. The big brake that I made below works no better than a standard KDF.

Capture[1] by Rod Henrickson, on Flickr

The most effective brake extant is the Armalite AR50 and AR30 brake; no holes; just huge panels to divert gas back..
Having fired both 90mm and 106 Recoilless Rifles, you quickly see what it takes to reduce recoil to zero; divert gas rearward.
You can't argue with the laws of physics. Aesthetics; you may argue.

Thanks, gentlemen.
As I said, couldn't see a reason it wouldn't work but had never thought of it so it was kind of a "lightbulb" moment when it was suggested.

Interesting comments on brakes, which is another issue I 'spouse but since Chucker brought it up....

I've long believed that trying to achieve very tight tolerances in brake bore clearance is unnecessary (and with a bit of fouling from a neglectful owner, potentially an issue). I get the point about deflecting as much gas as possible- and that a smaller brake bore will do that. But does it really matter if it's .020 over bore diameter- or .050 over? I just can't see it being a big deal that would measurably affect performance/felt recoil.

What say ye, Rod?

quote:

Originally posted by Big Gorilla But does it really matter if it's .020 over bore diameter- or .050 over? I just can't see it being a big deal that would measurably affect performance/felt recoil.

What say ye, Rod?

A little bit does not seem to matter much. The standard rule of thumb is .010 per side clearance. The reason we do that is because all barrels are crooked by about .004 inch over 29 inches. Well, they arn't really cooked, the drill itself drills in a helix from the cutting forces. I've gotten about the same number from every barrel maker that ever cared to comment and all of the reputable makers cull them out when they get much over that number. The old barrels, which are not drilled and reamed with modern methods can be much more. Also, certain calibers will kick their asses on exit of the barrel. It's not much and .308 and .284 seem to be the two worst offenders. .010 per side or .020 over bore diameter (same thing) seems to take all of those factors, plus a bit of good old fashioned human error into consideration and using that method you should never have a bullet strike unless something went totally wrong. Going a few thousandths of an inch over bullet diameter doesn't seem to make a lot of difference in the recoil reduction even though there is, logically a slight loss. Sort of like cutting the hood ornament off your car to better your fuel economy and make it go faster. Yes, in theory it does, in measurable practice, well good luck with that. When you do get vastly oversized, like using a .308 brake on a .284, yes, you start to get a noticeable loss of efficiency. But cutting it EGG-FAWKING-ZAKERY true to the bore and reducing the diameter to the point where you are about to get bullet strikes won't make it measurably more efficient.

I have never noticed an accuracy increase or decrease if the hole was or was not exactly in the center either. I have had some brought in that gave the odd strike, say one in 20 or so. Despite the unit being off center by .019 inch, after re-threading and centering the device, there was no real change in group size. Just no more flyers from the occasional strike. I can't say that there isn't some change in group size by having it perfectly centered, it is logically possible. I'm simply saying that on the brakes that I have seen that were badly cocked to one side or another and then later corrected, there was no measurable change in group size observed. But these are hunting rifles. Not bench guns and that makes minute changes very hard to detect.